Bevilacqua Lisa, Ramsey Jon J, Hagopian Kevork, Weindruch Richard, Harper Mary-Ellen
Dept. of Biochemistry, Microbiology and Immunology, Faculty of Medicine, Univ. of Ottawa, Ottawa, ON, Canada K1H 8M5.
Am J Physiol Endocrinol Metab. 2004 May;286(5):E852-61. doi: 10.1152/ajpendo.00367.2003. Epub 2004 Jan 21.
Reductions in cellular oxygen consumption (Vo2) and reactive oxygen species (ROS) production have been proposed as mechanisms underlying the anti-aging effects of calorie restriction (CR). Mitochondria are a cell's greatest "sink" for oxygen and also its primary source of ROS. The mitochondrial proton leak pathway is responsible for 20-30% of Vo2 in resting cells. We hypothesized that CR leads to decreased proton leak with consequential decreases in Vo2, ROS production, and cellular damage. Here, we report the effects of short-term (2-wk, 2-mo) and medium-term (6-mo) CR (40%) on rat muscle mitochondrial proton leak, ROS production, and whole animal Vo2. Whole body Vo2 decreased with CR at all time points, whereas mass-adjusted Vo2 was normal until the 6-mo time point, when it was 40% lower in CR compared with control rats. At all time points, maximal leak-dependent Vo2 was lower in CR rats compared with controls. Proton leak kinetics indicated that mechanisms of adaptation to CR were different between short- and medium-term treatments, with the former leading to decreases in protonmotive force (Deltap) and state 4 Vo2 and the latter to increases in Deltap and decreases in state 4 Vo2. Results from metabolic control analyses of oxidative phosphorylation are consistent with the idea that short- and medium-term responses are distinct. Mitochondrial H2O2 production was lower in all three CR groups compared with controls. Overall, this study details the rapid effects of short- and medium-term CR on proton leak, ROS production, and metabolic control of oxidative phosphorylation. Results indicate that a reduction in mitochondrial Vo2 and ROS production may be a mechanism for the actions of CR.
细胞耗氧量（Vo2）的降低和活性氧（ROS）生成的减少被认为是热量限制（CR）抗衰老作用的潜在机制。线粒体是细胞最大的氧气“吸收器”，也是ROS的主要来源。线粒体质子泄漏途径在静息细胞的Vo2中占20%-30%。我们假设CR会导致质子泄漏减少，进而使Vo2、ROS生成和细胞损伤减少。在此，我们报告短期（2周、2个月）和中期（6个月）40%热量限制对大鼠肌肉线粒体质子泄漏、ROS生成及全身体Vo2的影响。在所有时间点，CR组的全身Vo2均降低，而质量校正后的Vo2直到6个月时才恢复正常，此时CR组比对照大鼠低40%。在所有时间点，CR大鼠的最大泄漏依赖性Vo2均低于对照组。质子泄漏动力学表明，短期和中期处理对CR的适应机制不同，前者导致质子动力（Deltap）和状态4 Vo2降低，后者导致Deltap增加和状态4 Vo2降低。氧化磷酸化代谢控制分析结果与短期和中期反应不同的观点一致。与对照组相比，所有三个CR组的线粒体H2O2生成均较低。总体而言，本研究详细阐述了短期和中期CR对质子泄漏、ROS生成及氧化磷酸化代谢控制的快速影响。结果表明，线粒体Vo2和ROS生成的减少可能是CR作用的一种机制。
